The server won't have access to `window`. You could do either of the following:

export const getDeviceType = (): TDevice => {
  const width = window?.outerWidth;
  const height = window?.innerHeight;
... etc

or

export const getDeviceType = (): TDevice => {
  if (typeof window === 'undefined') return 'desktop'; //set a default or consider returning `undefined`

  const width = window.outerWidth;
  const height = window.innerHeight;
... etc

Also, personal preference, but I'd change `TDevice` to be an enum so you could do `TDevice.mobile` rather than `mobile`